The effects of sodium bicarbonate supplementation at individual time‐to‐peak blood bicarbonate on 4‐km cycling time trial performance in the heat
Lewis A. Gough, Jake J. Williams, Josh W. Newbury, William H. Gurton
Abstract
ABSTRACT The purpose of this study was to explore the effect of individualised sodium bicarbonate (NaHCO 3 ) supplementation according to a pre‐established individual time‐to‐peak (TTP) blood bicarbonate (HCO 3 − ) on 4‐km cycling time trial (TT) performance in the heat. Eleven recreationally trained male cyclists (age: 28 ± 6 years, height: 180 ± 6 cm, body mass: 80.5 ± 8.4 kg) volunteered for this study in a randomised, crossover, triple‐blind, placebo‐controlled design. An initial visit was conducted to determine TTP HCO 3 − following 0.2 g.kg −1 body mass (BM) NaHCO 3 ingestion. Subsequently, on three separate occasions, participants completed a 4‐km cycling TT in the heat (30 degrees centigrade; °C) (relative humidity ∼40%) following ingestion of either NaHCO 3 (0.2 g.kg −1 body mass), a sodium chloride placebo (0.2 g.kg −1 BM; PLA) at the predetermined individual TTP HCO 3 − , or no supplementation (control; CON). Absolute peak [HCO 3 − ] prior to the 4‐km cycling TT's was elevated for NaHCO 3 compared to PLA (+2.8 mmol.l −1 ; p = 0.002; g = 2.2) and CON (+2.5 mmol.l −1 ; p < 0.001; g = 2.1). Completion time following NaHCO 3 was 5.6 ± 3.2 s faster than PLA (1.6%; CI: 2.8, 8.3; p = 0.001; g = 0.2) and 4.7 ± 2.8 s faster than CON (1.3%; CI: 2.3, 7.1; p = 0.001; g = 0.2). These results demonstrate that NaHCO 3 ingestion at a pre‐established individual TTP HCO 3 − improves 4‐km cycling TT performance in the heat, likely through enhancing buffering capacity. Highlights This is the first time NaHCO 3 ingestion has been shown to improve 4‐km cycling TT performance in conditions of high ambient heat. A smaller dose of NaHCO 3 (0.2 g.kg −1 BM) is ergogenic in the heat, which is smaller than the dose typically ingested for sports performance (0.3 g.kg −1 BM). This is important, as gastrointestinal discomfort is typically lower as the dose reduces. This study suggests that the individualised time‐to‐peak HCO 3 − ingestion strategy with lower doses of NaHCO 3 is an ergogenic strategy in conditions of high ambient heat.